Polarization Conversion Element for Head-Up Displays

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Solution Overview

Problem

Existing head-up display devices require effective polarization axis rotation of display light to match the reflective surface shape, which existing technologies have not adequately addressed.

Innovation Solution

A polarization conversion element comprising a first and second substrate with a liquid crystal layer, a planar electrode, and a control electrode, where the alignment of liquid crystal molecules is controlled by voltage gradients to rotate the polarization axis of light to a desired direction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a reflective surface is used to rotate the polarization axis of display light, then the polarization axis can be rotated to match the reflective surface shape, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improvepolarization axis rotation capabilityVSAvoiddevice structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical/optical system of reflective surfaces for polarization rotation with an electric field-based liquid crystal system. By applying voltage to the liquid crystal layer, the polarization axis of transmitted light is rotated without requiring complex reflective surface geometries, thus reducing device complexity while maintaining adaptability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses voltage as a controllable parameter to dynamically adjust the polarization axis rotation angle. By changing the applied voltage, the liquid crystal molecules reorient, thereby changing the polarization direction of transmitted light. This provides adaptable polarization control without complex mechanical structures.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If a reflective surface is used for polarization axis rotation, then the desired polarization direction can be achieved, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvepolarization axis orientation controlVSAvoidreflective surface shape precision

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent substitutes the need for precisely manufactured reflective surfaces with a liquid crystal layer controlled by electrical signals. The voltage applied to the liquid crystal determines the polarization rotation angle, replacing mechanical precision requirements with electrical control, which is easier to implement and adjust.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces dynamic control of polarization axis orientation through variable voltage application. Instead of fixed geometric shapes requiring precise manufacturing, the system can dynamically adjust the polarization direction by changing voltage levels, providing flexibility without stringent manufacturing precision requirements.

Inventive Principle:

Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables the transmission of light with a polarization axis in a desired direction, enhancing the performance of head-up display devices by effectively rotating the polarization axis to match the reflective surface shape.

Implementation Method 1

a liquid crystal layer, a planar electrode, and a control electrode, where the alignment of liquid crystal molecules is controlled by voltage gradients to rotate the polarization axis of light

Methodology Applied

Scientific EffectLiquid crystal alignment control: Liquid Crystals

Implementation Method 2

rotate the polarization axis of light to a desired direction

Methodology Applied

Scientific EffectPolarization axis rotation: Polarisation

Data Source

PatentUS12050383B2Polarization conversion element

Publication Date: 2024.07.30 MAGNOLIA WHITE CORP

AI summary

According to one embodiment, a polarization conversion element includes a first wiring and a second wiring, a planar electrode, a control electrode including first strip electrodes, and a first alignment film, a second substrate including a second alignment film, and a liquid crystal layer. An alignment treatment direction of the first alignment film and an alignment treatment direction of the second alignment film are parallel to each other and cross an extension direction of the first strip electrodes. The control electrode overlaps the planar electrode in plan view. An applied voltage of the first wiring is configured to be higher than an applied voltage of the second wiring. The planar electrode is configured to have a voltage gradient.